Combined stain retardant and separator interleaving material for glass sheets

ABSTRACT

Sheets of glass are packaged, using in place of interleaving paper a dedusted agglomerated salicylic acid or a mixture of dedusted agglomerated salicylic acid and inert separator material, such as polystyrene beads. A novel method for agglomerating the acid is disclosed with the resulting salicylic acid agglomerated with polyethylene oxide and comprising substantially spherical particles less than about 30 mesh and having only a minor portion less than about 200 mesh. In accelerated staining tests agglomerated salicylic acid protects against staining slightly less than interleaving paper with its high application cost; agglomerated salicylic acid may be applied to sheets of glass with application costs on the order of those for applying wood flour or Lucite, which have extremely limited or negligible stain-retardant qualities, and this agglomerated material prevents surface scratching better than interleaving paper and nearly as well as an inert spherical separator.

United States Patent [191 Hay, Jr.

1 Mar. 27, 1973 [54] COMBINED STAIN RETARDANT AND SEPARATOR INTERLEAVINGMATERIAL FOR GLASS SHEETS [75] Inventor: William J. Hay, Jr., Cheswick,Pa.

[73] Assignee: PPG Industries, Inc., Pittsburgh, Pa.

[22] Filed: Dec. 18, 1970 [21] Appl. No.: 99,500

[52] US. Cl. ..252/ll, 65/24, 206/62,

252/381 [51] Int. Cl .,Fl6k 31/00 [58] Field of Search ..252/381, 384,11; 206/62;

[56] References Cited UNITED STATES PATENTS Primary Examiner-John D.Welsh Attorney-Chisholm & Spencer [57] ABSTRACT Sheets of glass arepackaged, using in place of inter leaving paper a dedusted agglomeratedsalicylic acid or a mixture of dedusted agglomerated salicylic acid andinert separator material, such as polystyrene beads. A novel method foragglomerating the acid is disclosed with the resulting salicylic acidagglomerated with polyethylene oxide and comprising substantiallyspherical particles less than about 30 mesh and having only a minorportion less than about 200 mesh. In accelerated staining testsagglomerated salicylic acid protects against staining slightly less thaninterleaving paper with its high application cost; agglomeratedsalicylic acid may be applied to sheets of glass with application costson the order of those for applying wood flour or Lucite, which haveextremely limited or negligible stain-retardant qualities, and thisagglomerated material prevents surface scratching better thaninterleaving paper and nearly as well as an inert spherical separator.

4 Claims, No Drawings COMBINED STAIN RETARDANT AND SEPARATORINTERLEAVING MATERIAL FOR GLASS SHEETS CROSS-REFERENCE TO RELATEDAPPLICATIONS This application is related to U. S. application Ser. No.99,651 also filed on Dec. 18, 1970 by William J.

Hay, Jr., Frank J. Pazul and Charles W. Lewis for Packing Material and aMethod of Packaging Glass Sheets, which is a continuation-in-part oftheir application Ser. No. 756,318, filed Aug. 29, 1968, now abandoned,and assigned to the assignee of the present invention. All of thatrelated application is here incorporated by reference.

BACKGROUND OF THE INVENTION This invention relates to a method forpackaging glass sheets wherein the glass is protected from staining andfrom mechanical surface damage by interleaving adjacent sheets of glasswith a chemically active stain retardant which is also a particulatesolid and which physically separates the glass and reduces frictionbetween adjacent sheets of glass when moved with respect to one another.More particularly this invention relates to a method of agglomerating astain-retardant agent. This invention relates also, in a differentaspect, to a stack of glass sheets having their surfaces protectedagainst staining and mechanical surface damage by layers of a finelydivided interleaving material comprising a stain-retardant support, suchas agglomerated salicylic acid, or a mixture of an inert support and astain retardant, one of said layers being positioned between eachadjacent pair of glass sheets.

It is known to package a stack of sheets of glass with the use of paperas interleaving material. Interleaving material affords protectionagainst staining but the methods known for applying interleaving paperare costly.

It is also known to use wood flour, Lucite or other particulate orfinely divided interleaving materials as mechanical separators toprevent surface scratching of adjacent glass sheets in storage. Methodsusing particulate interleaving materials are low cost methods but thematerials used afford little or no protection against staining duringstorage.

In accelerated staining tests at 140 F and 100 percent relativehumidity, wood flour or unmodified Lucite give a life of about one weekbefore staining is observed; interleaving paper protects glass fromstaining for about ten weeks.

British Pat. No. 861,578, issued in 1961, teaches the use of aninterleaving material, to protect sheet glass against staining, of amixture of a slightly acid agent and an inert material in solid form,more particularly in the form of a powder." A preferred example of theinvention is a mixture of sodium bisulfate with cellulose. We have trieda mixture of sodium bisulfate and Lucite, with the sodium bisulfatebeing used in an amount within the broad range indicated in the Britishpatent. The cellulose and the Lucite may both be considered inert. Inour tests, an interleaving material of sodium bisulfate as the activeagent did not appear to afford any advantage over wood flour as respectsstaininhibiting properties. Moreover, the cellulose material" referredto in this British patent is indicated as 2 possibly being wrappingpaper." This implies that the method of the British patent is notcharacterized by the cost savings that are obtained when there can beused as the interleaving material a particulate material such as Lucitebeads or wood flour.

SUMMARY OF THE INVENTION Sheets of glass are packaged, using in place ofinterleaving paper a finely divided particulate interleaving materialcomprising a dedusted agglomerated organic acid, with not more thanabout 4,000 square feet of glass surface being protected by one pound ofsuch interleaving material. The interleaving material is selected tohave sufficient physical strength to mechanically separate and protectadjacent sheets of glass. In addition to the agglomerated organic acidinert particulate separating material, such as wood flour, polystyreneor Lucite, may be present up to about a ratio of 4:1 with respect to theagglomerated organic acid. The particle size of agglomerated organicacid is less than about 20 mesh and preferably less than about 30 mesh;it is greater than about 400 mesh and preferably greater than about 200mesh; and if inert separator material is present its particle size ispreferably less than that of the acid so that initially the organic acidseparates and is in contact with the glass but after prolonged storageand volatilization or reaction of the acid the inert material remains toseparate the glass and protect against scratching.

Agglomeration of a stain-inhibiting agent, such as a solid organic acidparticularly salicylic acid or benzoic acid, is accomplished by mixingthe agent with a binder, such as polyethylene oxide; tumbling or rollingthe mixture to form substantially rounded, spherical or ovoidagglomerated particles generally having no sharp edges; drying theagglomerated particles by air-drying or contacting with absorbent ordessicant material; and screening the particles to yield a mixture ofagglomerated particles having a confined size distribution. The size ofthe agglomerated particles is limited by upper and lower constraints.The particles must be small enough to be easily applied to glass sheetsand retained on sheets in a steeply inclined position without rollingoff. The particles must be large enough, greater than 400 mesh, toprevent respiratory ingestion, and a substantial fraction of theparticles must be large enough to support adjacent glass sheets one fromanother. The stain-inhibitor particles are preferably agglomerated to arelatively large particle size and to rounded shapes so that they canserve to separate and support adjacent glass sheets and provide arolling action to prevent surface scratching if one sheet of glass ismoved laterally with respect to another.

Typically to 98 percent by weight of a useful agglomerated organicstain-inhibitor passes through a U. 5.. Standard Number 30 mesh screen,which permits particles smaller than 590 microns to pass, and at least50 to 60 percent by weight of the agglomerated organic stain-inhibitorparticles are typically retained on a U. S. Number mesh screen, whichpasses particles smaller than microns.

The organic acid must be selected according to its stain-inhibitingproperties as disclosed in the copending application herein incorporatedby reference namely U. S. application Ser. No. 99,65l filed Dec. 18,I970.

Use of salicylic acid agglomerated by mixing with polyethylene oxide iseffective to eliminate staining at 140 F and I percent relative humidityfor about 8 to 10 weeks or nearly as long as interleaving paper evenwhen it is mixed with an inert polystyrene in a ratio of 1:1; theapplication costs for use of this stain retardant particulateinterleaving material approximate those for use of wood flour or Lucite,which have no particular stain-inhibiting properties.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention generallycomprises a practice for packaging sheets of flat glass using, insteadof interleaving paper, a solid particulate organic acid or a particulatesolid impregnated with organic acid to both separate adjacent storedglass sheets and protect them from both staining and mechanical damage,such as scratching and marring. In addition to a particulate staininhibitor, an inert carrier or basis material may be included in theinterleaving material, with the .two being mixed in suitable proportionssuch as 1:2 to 4:1, inert material to active stain inhibitor. Suchparticulate stain-inhibiting interleaving mixtures are applied to glasssheets in quantities as limited as one pound per 4,000 square feet ofglass surface, but preferably in quantities somewhat more liberal suchas one pound per l,000 to 3,000 square feet of glass.

The particulate interleaving material may be applied to the glass bymechanical dusters or other particulate application equipment which isknown per se to those skilled in the art of dusting glass with woodflour, Lucite or other inert particulate interleaving materials.

In accordance with the invention, the inert or carrier materialcomprises any suitable inert and finely divided material, such as woodflour, polyethylene, polystyrene or methacrylate polyester (Lucite). Itis to be admitted that these materials, unmodified, have hitherto beenused as interleaving materials in the packaging of flat glass, but notincircumstances where it was intended that the glass be stored for asubstantial period of time. Lucite has an advantage over wood flour inthat it is somewhat physically stronger and serves to protect the glasssomewhat better against marring. On the other hand, wood flour, which isof a slightly acidic nature, may afford a slight advantage over Lucite,which is completely neutral and inert, in respect to the extent of staininhibition. Neither of the materials, unmodified, affords to the sheetsof flat glass to be packaged any protection against staining remotelyapproaching that afforded by the relatively more costly practice ofusing interleaving paper.

Those skilled in the art wiil appreciate that as the inert material orcarrier material thereof, in the interleaving material there may also beused beads or small particles of other materials such as polyethylene,polystyrene, polytetrafluoroethylene, etc. In general, it is desirablethat the material be relatively finely divided, such as about mesh, andfree-flowing. Preferably, the carrier material is somewhat finer, beingless than about 30 mesh and most preferably is less than about 60 mesh.The material should be such as to exhibit suitable handlingcharacteristics, enabling it to be fed onto the glass by means ofcommercially available equipment for handling and feeding finely dividedsolids.

The stain-inhibiting agent, according to the preferred embodiments ofthe invention, is a dedusted and agglomerated salicylic acid. Dedustingis desirable to reduce or eliminate potential handling problems due toslight toxicity of salicylic acid, which could cause irritation toworkers handling such protected glass in the absence of protectiveclothing or equipment. Agglomeration of the salicylic acid to grains orparticles of controlled size and substantially spherical shape providesthe acid as a stain-inhibiting agent having appropriate physicalcharacteristics to separate glass sheets and provide a rolling actionbetween adjacent sheets when they are laterally moved with respect toone another.

In the most preferred embodiment salicylic acid is agglomerated withpolyethylene oxide and methanol to form substantially spherical grainsor particles of which to 98 percent pass a 30 mesh screen. Thisagglomerated acid is mixed with an equal amount by weight of inertcarrier, such as polystyrene, which comprises substantially sphericalparticles of lesser diameter than the agglomerated acid, preferably lessthan about 60 mesh. This interleaving material, when placed betweenglass sheets in storage, protects the glass from staining and fromphysical surface damage. Under magnification, for example, 50 times, thepolystyrene may be observed as almost perfect spheres which aresubstantially smaller particles than the agglomerated salicylic acid.The size of the polystyrene spheres in the preferred embodiment is aboutNo. 60 U. S. mesh. The agglomerated salicylic acid grains will beobserved to be substantially spherical with diameters 4 to 10 times thatof the polystyrene particles. The agglomerated salicylic acid grains aretypically about No. 20 U. S. mesh and are generally less than about No.30 U. S. mesh.

It is thought desirable to have the agglomerated acid act as thephysical separator initially for intimate glassstain-inhibitor contact,and it is though that as the organic acid volatilizes and reacts toprevent staining, the separation between adjacent glass sheets decreasesaccording to the decreasing size of the agglomerated acid particlesuntil separation is maintained by the inert carrier. It is thought thatthis expected decrease of spacing between glass sheets during storagecombined with the corresponding volatilization of the organic acidinsures complete contact, over the full glass surface area, between theglass and the acid or its vapors. This is thought to effectively excludeentry of water vapor between the sheets of glass and to effectivelyprotect the glass uniformly over its surface. Though the mechanism bywhich the observed beneficial effect occurs is not fully understood, itis thought that having a stain inhibitor and separator as a singlematerial yields benefits beyond the mere additive effect of the separatefunctions of a single stain inhibitor and a single inert separator ofequivalent particle size.

In a second preferred embodiment agglomerated salicylic acid is usedalone without any inert carrier. Until glass has been stored for so longthat the acid is dissipated, this interleaving material protects asfully against staining and mechanical surface damage as that of the mostpreferred embodiment, but upon dissipation of the stain-inhibitingsalicylic acid no inert separator remains to protect against surfacemarring. Also, excess usage of salicylic acid may be avoided by thedilution afforded by addition of inert carrier, as in the most preferredembodiment.

As the stain-inhibiting agent, materials other than salicylic acid maybe found useful. Dedusted benzoic acid has a stain-inhibiting effectsubstantially on the order of that of salicylic acid, but it is perhapsa little less advantageous because of greater problems of handling,toxicity of irritation. Dedusted toluic acids have been found in ouraccelerated-staining tests to exhibit substantial stain-inhibitingproperties, but at a given level of application (square feet of glassper pound of stain-inhibiting material), they are substantially lesseffective than either salicylic acid or benzoic acid. A reasonableamount of stain-inhibiting activity has been observed in adipic acid,which is substantially non-toxic. But a linear acid having threecarboxyl groups, such as citric acid, inhibits staining only about aswell as wood flour.

Useful stain-inhibiting agents thus comprise cyclic organic acids andlinear organic acids having no more than two carboxyl groups. Preferredacids have a substantial vapor pressure at room temperature. In ouraccelerated-staining tests, we have not yet found any suitable inorganicstain-inhibiting agents, i.e., ones that afford a level of protectionagainst staining such as that obtained with dedusted salicylic acid orwith paper.

The stain-inhibiting agents are preferably agglomerated usingpolyethylene oxide but other binders, such as polyethylene glycol andpolyvinyl pyrrolidonevinyl acetate copolymer (about 40 percent 'vinylacetate) are suitable as well. Acids impregnated into porous, solid,inert separator materials perform less suitably than agglomerated acids.

The accelerated-staining test is conducted by applying to the topsurfaces of all but one of a suitable number, such as about five, ofsample pieces of mirrorquality plate glass (about 8 by 10 inches) apredetermined quantity of the interleaving material'to be tested, namely(unless otherwise specified) 2,000 square feet of glass per pound ofmaterial; stacking the sample pieces and clamping them together; thenexposing the clamped stack, with the sample pieces held so that they liein generally vertical planes, in a chamber under conditions ofl00percent relative humidity and 140 F; and then withdrawing a clampedstack from the chamber after a period of time and washing the glass withwater and inspecting it to determine whether staining has taken place.In a test of this kind, staining is usually observed within three daysto one week if wood flour or untreated beads of Lucite are used as theinterleaving material, whereas, when interleaving paper is used,staining is usually not observed until the clamped stack has been soexposed for about 10 to 12 weeks.

The accelerated-staining test described above is considered quite severein that the exposure of the glass to moisture is promoted to levels farabove those ordinarily encountered, and it takes place at a temperaturewell above those ordinarily encountered in storage, so that whateverchemical reactions, etc., are causing the staining, they would beexpected to accelerated. Moreover, in our tests we have used plateglass, which, like window glass, is considered somewhat more prone toexhibit staining than flat glass produced by the float process. Inpractice, staining is encountered with all three kinds of flat glass. Itis not often a problem with glass stored for less than three monthsunder normal rather than hot, moist conditions. This is so even if theinterleaving material is one having little or no stain-inhibitingeffect, such as wood flour or unmodified Lucite.

The staining problem in its practical and commercial aspect is properlyto be viewed from the standpoint of probability; there is a probabilitythat a given piece of glass will be stained before it can be used, andthis is influenced by a great number of relevant factors, such as thekind of glass, length of storage, the temperature and humidityconditions during storage, and the kind of interleaving material used.Sometimes float glass packed in interleaving paper and stored for fourmonths under cool, dry conditions will stain, and sometimes plate glasspacked in wood flour and stored for ten months or more under hot, humidconditions will not. These exceptional results serve to show theuncertainties of protecting against glass staining but do not alter theprobability that certain conditions will aggravate staining. Theusefulness of the instant invention is that it appears to yield results,so far as the effect of interleaving material is concerned, thatapproach those obtained with interleaving paper, without being so costlyto practice as paper-interleaving.

To find a commercially satisfactory substitute for the known practicesis not an easy matter. If the stain-inhibiting agent, though effective,is even mildly deliquescent, it may create handling problems in thefeeder by which it is supplied to the glass. It must be capable of beingmade available in a form finely divided enough to mix with the woodflour or Lucite or other material, and at the same time not so powderyor dusty as to create handling, irritation or toxicity problems. We havenot yet found a liquid stain-inhibiting agent that is effective and atthe same time nonvolatile enough that it can be expected to havelonglasting effects. Some of the organic acids that are asstain-inhibiting as dedusted salicylic acid, or perhaps more so, arepowerful skin irritants or lachrymators and would thus raiseconsiderable safety problems, both in the operations of a glassmanufacturer and in the operations of a glass manufacturers customers orwarehousemen. indeed, salicylic acid itself, if not dedusted, in onlymarginally suitable for this very reason. It must be possible for theinterleaving material to be removed readily from the glass before it isused. it is conceivable that a stain-inhibiting agent may comply withall the other requirements but prove useless because of its high costand/or its poor availability. The number of candidate stain-inhibitingagents to be considered is very large, and when the determination of anappropriate and effective level of usage is also to be taken intoaccount, the amount of research that can be devoted to the problem isenormous, but the applicant has considerably advanced the art bylearning how to use dedusted agglomerated salicylic acid either along orin combination with an inert separator material. The discovery of theapplicant that an agglomerated organic acid of selected particleconfiguration and size can be used to support the separation of glasssheets and at the same time retard staining in a manner which appearssuperior to that obtainable with other particulate interleavingmaterials appears to portend benefits beyond the specific organic acidsalready tested. Organic acids may be selected for their volatility,particle size and configuration (possibly expressed as specific surfacearea in the alternative) and for their susceptibility to agglomerationand their shape-control characteristics, and such organic acids may beused along or in combination with inert carrier materials, preferably ofsmaller particle size, as interleaving material for glass sheets toinhibit staining and protect against glass surface damage, such asscratching or marring.

The invention described above is illustrated by the following Examples.

EXAMPLE I An interleaving material having constituents in the followingquantities is prepared.

parts, Salicylic Acid 5 pounds 0.13 parts, Polyethylene Oxide 60 grams0.17 parts, Methyl Alcohol 80 ml 5 parts, Polystyrene 5 pounds Into aneight quart-liquid solids blender (e.g., P-K blender manufactured byPatterson-Kelly Company) are charged the salicylic acid, which isunsublimed technical grade acid, and the polyethylene oxide (e.g., WSR-Nl0, sold by Union Carbide). After a one minute premix, with the blenderintensifier still on, the methanol (of technical purity) is added overabout 30 seconds. About 15 seconds after the last methanol enters themixer, the intensifier bar is turned off. The shell of the blender isallowed to continue rotating for about 10 to minutes. The agglomeratedmaterial is removed from the blender and air-dried and screened. About90 percent of the agglomerated salicylic acid passes a 30 screen. Allscreen sizes correspond to U. S. Series equivalent mesh screens.

Polystyrene (e.g., Dylene 8, No. 60 Fines, sold by Sinclair-Koppers) ismixed with the agglomerated salicylic acid and the constituents mixed inthe blender or in a drum mixer or by hand tumbling.

This mixture of dedusted agglomerated salicylic acid and polystyrene isapplied to the surface of glass sheets as interleaving material withabout one pound of material used per thousand square feet of glasssurface. The glass sheets are stacked and clamped together. Several setsof glass sheets are prepared.

The stacked glass with interleaving between each adjacent pair of sheetsis placed in a test chamber. The glass in the chamber is subject toaccelerated staining test conditions. Temperature within the chamber ismaintained at about 140 F. Relative humidity within the chamber ismaintained at about 100 percent by maintaining a puddle of water on thefloor of the chamber.

The stacked glass is held in the chamber for periods of 1 week to 10weeks. The glass is then removed. The clamps are removed and the glasssheets unstacked. Each sheet is washed clear of interleaving materialusing water. The glass sheets are then visually inspected for iridescentstaining. Those glass samples held in the chamber less than eight weeksexhibit no visually apparent staining. Some staining of samples held tenweeks in the chamber is observed.

While methyl alcohol is used as a solvent in the agglomeratingprocedure, and is particularly useful in this function, any otherconvenient organic solvent may be used to insure that all thepolyethylene oxide binder is intimately mixed with the salicylic acid toagglomerate it.

EXAMPLE ii The test of Example l is repeated except no polystyrene isused. Stain-test results are identical.

The effectiveness of the invention with respect to protection againstabrasion may be deduced from the following tests.

TEST l INTERLEAVING PAPER interleaving paper is placed between a numberof pairs of 4-inch-square plates of polished glass. In turn eachtwo-plate sample is placed in a Taber-Abraser test device, with the oneglass plate fixed to the stationary base and the other glass plate fixedto the rotating head. A SOO-gram load is imposed on the glass plates.One set of samples is subjected to abrasion for 300 revolutions; asecond, for 600; and a third, for 900.

After the plates are rotated to induce abrasion damage, they are removedfrom the testing machine and examined in a light from a point source todetect scratching. All samples exhibit light scratching forthe setevolved 300 times, and heavy scratching for the other sets.

polystyrene. No scratching is observed for the test revolved 300 times.About 25 percent of the plates in the set revolved 600 times arescratched. About 50 percent of the plates in the set revolved 900 timesare scratched.

TEST Ill SALICYLIC AClD The procedure of Test I is repeated, except thatthe glass plates are separated by about 30 mesh agglomerated salicylicacid with no polystyrene. No scratching is observed for the setrevolved'300 times. About 50 percent of the set revolved 600 times havescratches. All of the set revolved 900 times are scratched.

The above test show that agglomerated salicylic acid alone can protectglass sheets from mechanical surface damage.

The above examples and descriptions of the invention are not to beconsidered limiting, for, as will be apparent to one skilled in the art,many variations in material selection may be made without departing fromthe spirit of this invention.

1 claim:

1. A method of preparing an agglomerate material for packaging glasssheets comprising the steps of:

mixing an organic acid selected from the group consisting of cyclicacids and linear dicarboxylic acids with a binder selected from thegroup consisting of polyethylene oxide, polyethylene glycol, polyvinylpyrrolidone-vinyl acetate copolymer and mixtures thereof;

tumbling the mixture of organic acid and binder so as to roll themixture into substantially rounded agglomerated particles ofsubstantially uniform size glomerated organic acid to (b) about twoparts inert separator to one part agglomerated organic-acid.

3. An agglomerate material suitable for packaging glass sheets toprotect them from staining and scratching, comprising an organic acidselected from the group consisting of benzoic acid,'salicyli'c acid,toluic acid, .adipic acid and mixtures thereof agglomerated with abinder selected from the group consisting of polyethylene oxide,polyethylene glycol, polyvinyl pyrrolidone-vinyl acetate copolymer andmixtures thereof to form substantially rounded particles ranging fromabout U. S. Number 30 mesh to about U. S. Number 200 mesh, said organicacid being admixed in a ratio of from about one to four to about two toone with an inert separator material selected from the group consistingof wood flour, polyethylene, polystyrene, polymethylmethacrylate,polytetrafluoroethylene and mixtures thereof having substantial roundedparticles ranging from about U. S. Number 60 mesh to about U. S. Number200 mesh.

4. The method of preparing an agglomerate accord ing to claim 1 whereinthe inert separator is selected from the group consisting of wood flour,polyethylene, polystyrene, polymethylmethacrylate,

1 polytetrafluoroethylene and mixtures thereof.

it i 8 i i UNITED STATES mrmmr orritr QERTHFHQATE @E REETEN Patent No. 3723 312 Dated March 27. 1973 Inv nt William J-. Hav. Jr.

It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

Claim 2, Column 9, line 10, "8" should be l Signed and sealed this 18thday of September 1973.

(SEAL) Attest:

EDWARD M.PLETCHER,JR. RENE D. TECTMEYER Attesting Officer ActingCommissioner of Patents FORM PC4050 ($59) USCOMM-DC 60376-P89 U.S,GOVERNMENT PRINTING OFFICE: 969 0-365-33.

2. The method of preparing the agglomerate material of Claim 8 whereinthe inert separator is mixed with the agglomerated organic acid in anamount ranging from (a) about one part inert separator to four partsagglomerated organic acid to (b) about two parts inert separator to onepart agglomerated organic acid.
 3. An agglomerate material suitable forpackaging glass sheets to protect them from staining and scratching,comprising an organic acid selected from the group consisting of benzoicacid, salicylic acid, toluic acid, adipic acid and mixtures thereofagglomerated with a binder selected from the group consisting ofpolyethylene oxide, polyethylene glycol, polyvinyl pyrrolidone-vinylacetate copolymer and mixtures thereof to form substantially roundedparticles ranging from about U. S. Number 30 mesh to about U. S. Number200 mesh, said organic acid being admixed in a ratio of from about oneto four to about two to one with an inert separator material selectedfrom the group consisting of wood flour, polyethylene, polystyrene,polymethylmethacrylate, polytetrafluoroethylene and mixtures thereofhaving substantial rounded particles ranging from about U. S. Number 60mesh to about U. S. Number 200 mesh.
 4. The method of preparing anagglomerate according to claim 1 wherein the inert separator is selectedfrom the group consisting of wood flour, polyethylene, polystyrene,polymethylmethacrylate, polytetrafluoroethylene and mixtures thereof.